Gage.



No. 652,666. Patented .lune 26, |900. P. J. DARLINGTDN.,

GAGE.

(Applicption filed Dec. 5. 189B.)

(No Model.) 4 heeis-$heet I.

G A G E (Application led Dec.

4 Sheets-Sheet 2.

(No Model.)

, 5U M# W Tu: "cams Penas on. umu-Lune.. wumusmn. o. c4

No. 652,666. Patented 4lune 26, |900.. P. J. DARLINGTUN.

GAGE.

(Application filed Dec. 5,- 1898.)

(No Model.) W4 Sheets-Sheet 3.

Nn. 652,666. Patented lune 26, |900. P. J. DARLINGTON. GAGE.

(Application filed Dec. 5, 1898.) (N0 Nudel.) 4 Sheets-Sheet 4.'

Ni'rnn ATS PHILIP J'. DARLINGTON, OF MONTREAL, CANADA.

GAGE.

SPECIFICATION forming part of Letters Patent No. 652,666, dated June 26, 1900. `Airplication iiled December 5, 18948. Serial No. 698,354. (No model.)

To all whom, t mag/conccrm Beit known that I, PHILIP J. DARLINGTON, of the city of Montreal, Province of Quebec, Dominion of -Canada, have invented certain new and useful Improvements in Gages; and I do hereby declare that the following is a full, clear, and exact description of the same.

My invention has for its object to provide means to ascertain the resistance to or Working pressure upon different areas of the surface of any solid in contact with a liuid or of the surface of any intermediary or agent through which motive power is derived by an object, machine, or the like from the resistance offered to said intermediary or agent or the pressure` exerted thereupon by a iiuid,`

vwhether liquid or gaseous.

As an instance where my invention is particularly applicable I may mentionwhat is known as pounding in ocean-going vessels., The mostlpopular theory is that this pounding is'due rto the passing of the propeller-blades through areas of different resistance--as,'for instance, when the blades pass from the (comparatively speaking) loose water nearthe highest point of its revolution relatively to the surface of lthe Water to the more compact mass near the lowest point thereof. The embodiment'of my invention hereinafter describedin detail and illustrated in the drawings will enable, first, the maximum and minimum degrees of resistance offered to the surface'of a propeller-blade dur-' ing its revolution to be ascertained, and, secondly, to ascertain the precise degree of resistance offered to anyone defined area or more different defined areas of the surface of a propeller-blade at any predetermined angularposition during its revolution.

The invention may be said broadly to consist in providing'the surface of an intermediary or agent such as before mentioned with one or more'device's 'adapted to-be held by a known and variable countervailing pressure or force against the fiuid in conjunction with which said intermediary or agent may be designed to act to impart motive power to the object, machine, or thelike to which said intermediary or'agent may be connected, providing means for increasing or diminishing` said countervailing pressure or force until it is equal to the resistingforce of the Huid, and i providing means to indicate at what degree fthe countervailing pressure or force equaliaes the resistingV force of the fluid, thereby ascertaining precisely the degree of resisting force of' the liuid' upon said device or devices carried by the agent.

More specifically speaking, the preferred embodiment of my invention may be said brieiy to consist in mounting one or more pressure devices in the form of diaphragms in that face of a propeller-blade the resistance to which it may be desired to ascertain, the outer face of each diaphragm being adapted to be acted upon by the water, While the inner face thereof communicates with an airtank, means being provided to increase or diminish the pressure of air in said. tank and said tank having a pressure-gage to register `thepressure therein. Anelectric circuit is suitably arranged to include a pair of contactpieces, which are carried one by the diaphragm and the other adjacent thereto by the body of the blade. A second pair of contactpieces included in a branch of said circuit are carried one by a part moving with the propeller and the other by a part free of said first-mentioned part and adjustable along the line of movement of said moving part in order that said adjustable part may be adjusted to cause the contact-piece carried thereby to register with' any predetermined point in the cycle of movement of said moving part and by consequence with a corresponding predetermined angular position of the blade. A switch is included in said main circuit,where by thebranch circuit can be cut out, While a commutating-switch, also included in said main circuit, enables any particular pressure ydevice to be included in the circuit. For full comprehension, however, of my invention in its entirety reference must be had to the accompanying drawings, forming apart of this specification, in which like` symbols indicate Vthe same parts, and wherein- Figure l is a detail diagrammatical View of a propeller and a portion of its shaft with my invention applied thereto. Fig. 2 is a detail elevation ofthe aft face of a propeller-blade with a series of these pressure devices set therein. Fig.` 3 is an elevation of the forward face of said blade. Fig. 4 is an enlarged plan view, partly broken away, of one of the pres- IOO sure devices. Fig. 5, atransverse vertical sectional view thereof, taken on line 5 5, Fig. 4. Fig. 6 is a horizonal sectional View taken on line 6 6, Fig. 5; Fig. 7isa detail end elevation of the means for coupling the air-conducting pipe from the tank to the air-passage from the air-chamber of the pressure-devices. Fig. 8 is a detail plan view thereof, partly in sectional View, the sectional View being taken on line S 8, Fig. 7. Fig. 9 is an end View of the collector for receiving the electric current from the wires leading from the contactL points upon the com mutatinglswitch and transmitting it to the wires leading to 'the pressure devices. Fig. 10 is a plan view thereof, partly in sectional view, the sectional view being taken on line 10 10, Fig. 9. Fig. l1 is an enlarged detail sectional View, taken also on line 10 10, Fig. 9, of the contact-rings and their carrying-rings. Fig. 12 is an end View of the adjustable contact device through which they pressure upon any required defined area of the surface of a blade may be ascer- Fig. 13 is a plan view thereof, partly in sectional vi'ew, the sectional View being taken oir line 13 13, Fig. 12. Fig. 14 is an enlarged detail sectional view taken also on line 13 13, Fig. 12, and illustrating particularly the preferred manner of mounting the contact-pieces carried by said adjustable contact device; and Fig. 15`is a detail end elevation of the adjustable' ring for carrying the contact-ring.

The shaft l5 is, as usual, hollow, and the manner of mounting and driving same will of cou-rse be according to the work to be done and constitutes no part of my invention.

The propeller consists of a hub 16, having aseries of blades 17 rigidly secured thereto. The aft face of the blade has three circular recesses 18, 19, and 20, respectively, cut therein,.and the floor of each of these recesses has a shoulder 2l formed at the edge thereof and an outwardly-projecting circular broken ridge 22X, of small diameter relative-ly to each recess, formedconcentrically thereof and consti-tutin-g` a seat for a pressure-block. This pressure-block is clearly illustrated in Figs. 4, 5, and 6 and consists of a circular resilient metallic diaphragm 22 and a circular solid metal dfisk 23. The diaphragm has its edge turned outward, as at 24, to afford a firm hold for a retaining-ring 25, which holds the edgeof the diaphragm rigidly upon the shoulder by means of a series of screws 26, taking through said ring and the diaphragm into said shoulder. The diaphragm has a central opening 27, the edges whereof are soldered or otherwise rigidly connected to the recessed edge of a hub-section 28, formed upon the inside fac'e of the disk 23. This circular disk is of a diameter to closely lfit within its recess 20, and the outer face thereof conforms to the surface of the blade. A contact-piece is carried by this disk concentrically thereofV and consists of a plug 30, having a head 3l central perforation in the disk. this plug takes through a grooved boring 35 in the body of the blade and extending from series of grooves 39.

. ner end communicates. n are secured inplace electric conductors, consisting of insulated copper wires 47, 48, and

formed upon one end thereof, the other end thereof being formed with a screw-threaded boring to receive the end ofta screw 33, takingI inwardly through a iiared screw-threaded The body of the center of the recess 2O to the opposite or forward side of the blade, the portion of said boring adjacent to said forward face of the blade being enlarged to accommodate the K' head of the plug and a small fibrous disk 36 and at the same time afford a shoulder 32 vto restrict the extent of displacement of the pressure-block away from its seat, as will be hereinafter clearly set forth. The fibrous disk. 36 carries a contact-pin 3S, rigidly set i therein and having the forward end insulated, and the edge of suchv disk i's formed with a The outer end of ther enlarged portion of the boring is closed by a disk 41, taking therein and resting upon a shoulder formed bya further enlargement of tained when the blade is in any predeteri mined angular position during its rotation. g

said outer end.

When three pressure devices are used, they are preferably distributed over the aft surface of the blade, as shown in Fig. 2, and the respective air-chambers 40 behind the diaphragms communicate with one another through chambers formed in the following f manner, reference being had particularly to Figs. 2 and 3: A series of rectangular grooves 42,'having inward semicircular extensions 43, i are cut inthe forward faceof the blades-t'. e., the face opposite to that in which the pres- 3 sure devices are set-and extend,respectively, 1 one fromy the cham-ber of the radially-outerf most pressure device indicated at 1, Fig. 2, to 1 the chamber of the pressure device indicated z at 2, a second one from the chamber of device 2 to and communicating with the outer end of a diagonally inwardly extending bort ing 45, while a third groove extends from the vpressure device indicated at 3 also to and :communicating with the upper end of said f boring 45. i into each of the grooves 42'and secured therein by any suitable packing that will make i each of the grooves 43 air-tight. Lend of this boring communicates with the y outer end of a short pipe 46, which extends fcentripetally through the blade, hub, and

A rectangular strip 44 is iitted The inner shaft, with the interior lof which latter the in- B'efore the strips 44 49, are electrically connected at their outer ends to the contact-pins 38 of the respective pressure devices 1, 2, and 3 and taken through the grooves 43, boring 45,'and pipe 46 into and along the interior of the shaft, as shown in Figs. 1 and 5. The outer end of the shaft is closed, as usual, by a cap 50, and the interior thereof is divided at the inner end of the first shaft-section by a transverse dia- :phragm or plug 5l, thus providing a main air-chamber 52, communicating through the IIO pipe 4G, boring 45, and air-tight channels 43 with the` respective air-tight chambers 40 of the pressure devices. An air-passage 68 is bored through one side of the shaft to communicate with the interior thereof, and the outer end of this passage is coupled to the inon and communicating with the interior thereof, while a valve 5S, to be utilized as an airvent under certain conditions, is located at the juncture of the pipe 5i and said reservoir.

The coupling just mentioned is clearly shown in Figs. 7 and 8 and consists of an annulus 60, divided in an axial plane and secured together and tightened upon the shaft by screw-bolts and having a pair of centrolineally projecting ridges 6l, adapted to closely fit the shaft and form an annular airchamber G2, encircling said shaft. This airchamber is made air-tight by a pair of stuffing-boxes constructedof a pair of rings G3 G3, divided in ,an axial plane, as at G3", and L shape in cross-section to take into the spaces between the edges of the annulus and the shaft and at the same time extend across the faces of saidedges and receive adjusting- .screws 64, adapted to take therethrough and into the said edges, while a pair of stuffingrings 65 are located between the inner edges of these L-rings and the ridges. Aradiallyprojecting arm G6 is formed integrally with said annulus and to one side thereof and is supported at its end from the fioor by a leg 67. A passage 08 is bored transversely through the shaft to afford a communication between the interiorof said shaft and the annular chamber 62, and a' boring 53 radially through the annulus provides a passage,ivith the outer end whereof the pipe'54 is connected'by an air-tight connection. This construction, as is obvious, allows the shaft to rotate without interfering with the communication from the air tank or reservoir to the three chambers of the pressure devices.

The electric conductors 47, 48, and 49 are taken out from the interior of the shaft through a diagonal passage 70,Whieh is sealed, and they are electrically connected, respectively, by an improved electrical collector h (to be presently described) to the ends of three conductors 4, 5, and 6, electrically connected, respectively, at their opposite ends to contact points or terminals 7, 8, and tl upon a commutating switchboard 10, having a switch-lever ll fulcrumed thereon. A wire 12 leads from this switch-lever to one of the terminals of a short-circuit switch 13 and thence to one of the terminals of an adjust-1 terminal of this contact device to the other terminal of said switch 13 and thence through a current-indicator m to an electric battery 7c and to ground.

My improved collector (see Figs. 9 and l0) consists of a circular box 7l, divided in an axial plane and having the parts thereof connected together and clamped rigidly upon the shaft by a pair of screw-bolts 72, taking through ad j oinirig perforated lugs 73, formed upon the abutting edges of a pair of axiallyextending fianges 74, formed integrally with the opposite ends of said box and having circumferential depressions or notches 75. A radially-extending'circumferential iiange 7 6 is formed on the exterior of the box and has three brass contact-rings 77, 7S, and 79 electrically separated from one another and from said flange by fibrous insulation-rings SO, secured thereto by means of a clamping-ring Sl and screw-bolts S2,Which latter and the clamping ring are also respectively electrically separated from the contact-rings by fibrous insulating-bushings and rings 83 and Si, respectively, and the contact-rings are electrically separated from the surface of the box 7l by a sheet of insulating material 7l. A pair of divided rings 85 encircle the iianges 74, taking into the circumferential depressions therein, and each has a radially-projecting arm S6, formed integrally therewith and connected together at their ends by a localizing-sleeve 87, and a spindle SS, taking through said ends and the sleeve and having its ends screw-threaded to receive jam-nuts 89 and a pair of nuts 90, between which and said jam-nuts the upper perforated ends ofa pair of supportinglegs Jl are secured, the' lower ends thereof being oii'setand bolted to the timbers of the vessel. Adjacent to the end of the frame thus formed the outer ends of three brushes 92, U3, and Oat are supported upon a spindle 95, made of wood or other in'- sulating material and held in place with its ends in perforations in' the arms S6 of the frame by a pin 9G. These brushes are insulated from one another and localized relatively to the respective contact-rings 77, 78, and 79 by fibrous cylindrical sections 97, taking over the spindle 95, while the inner ends thereof are conformed to and bear upon said contact-rings, and their outer ends have the ends of the wires or conductors 45, and G, respectively, connected thereto. A pair of spindles 9S support said inner ends of theV brushes between them and are constructed of Wood, liber, or other insulating material and mounted and held in place with their ends in the arms 86 of the'frame similarly to the` spindle 95.

The adjustablecontact device that l have devised and that I consider as most-suitable for the function required of it is constructed and mounted as follows, reference being had` to Figs. 1l, l2, 13, and la: iA circular box 100, somewhat similar to the box 7l, encircles the ,shaftV and is rigidlysecured thereon to rotate IOC TOSv

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therewith similarly to said box 71. Oppositely-extending ianges 101 102 are formed in one With the edges of said box 100 and are provided with circumferential depressions 103 104, respectively, the depression 104 being of greater-width than the depression 103. The latter depression 103 receives a ring 105, similar to the rings 81, and the depression 104 receives a ring 106, which closely fits therein, While each of said rings is frmed with a radially-projecting arm 107. These arms are connected together and localized relatively to one another by a spindle 108 and sleeve 109, the ends of the spindle, like the spindle S8, being connected to a pair of supportinglegs 110, similar to the legs 91, and a wooden spindle 112 is rigidly mounted at its ends in the arms 107. A pair of contact-brushes 113 114 are supported at their outer ends upon said spindle 112, and are separated by fibrous cylindrical sections 115 from the arms and one another, the inner ends of these brushes being supported between a pair of wooden spindles 116 and conforming to the surface of a pair of contact-rings 117 ll8,respectively,while the outer ends of these brushes have one end of each-of:` the respective wires 12 and 14 counected thereto. The manner in which these contact-rings are carried is clearly shown in Fig. 13.

The contact-ring 117 is mechanically connected to a radially-projecting circumferential iiange 120, formed upon the exterior of the box 100 by a contact-pin 121 passing through said flange and contact-ring and receiving a nut 122. A brous bushing 123, a ring 124, and a sheet 125, also of fiber or otherinsulating material, electrically separates said contact-ring and the contact-pin 121 from the flange and the surface of the box, respectively, while a fibrous insulating-ring 126 is located on the opposite side of the contactring. These various parts are clamped rigidly together by a clam ping-ring 127 and a series of bolts 128 taking therethrough and through the insulating-rings, contact-ring, and ange, and receiving-nuts 129, the bolts of course lbeing insulated from the contact-ring.

The contact-ring 118 is carried rigidly upon a rotatably-adjustable ring 130, L-shaped in cross-section and mounted upon the ring 106, to which it is adj ustably connected by means of a radially-projecting circumferential flange 131, through which project a series of screws having conical heads 132, adapted to take into a dovetail circumferential groove 133, formed in the adjacent face of the ring 130, while the other ends of said screws receive clamping butteriiy-nuts 134. A pair of rings 135 136 and a strip 137 of ber or other insulating material electrically separate the contact-ring 118 from its carrying-ring 130,

and a short sleeve 138, of brass or other electro'conducting material, is set in the said contact ring and projects laterally therefrom through one of the insulating-rings toward the contact-ring 117. A contact-pin 139 slides in this sleeve and is formed with a rounded head 140 upon one end and has a collar '141 riveted upon its other end. A coiled spring 142 encircles said pin and bears between said head 140 and the insulating-ring 13G, which -is recessed to accommodate it and the moveshould be placed upon contact-point 7, thus closing a circuit from battery 7c through Wire 14, current-indicator m, short-circuit switch 13, (which should be closed,) wire 12, commutating switch-lever 11, contact-point 7, wire 4 to the collector, through brush 92, contact-ring 77, Wire 47 to the pressure device,

and through the contact-pin 38 and contactplug 30 to ground in the Water. It is obvious that the current will run through this circuit and be indicated by the indicator m so longgas the resistance to the outside of the diaphragm22 exceeds the pressure uponthe inside thereof, and consequently the pin 38 and plug 30 are in contact with one another. The maximum resistance to the' pressure device is ascertained by compressing air by means of the compressor 56 in the tank 55 and through pipe 54, annular air-chamber 62, air-passage 68, air-chamber 52 within the shaft, pipe 46, boring 45, channel 43, grooves 39 of disk 36, and through the grooved boring 35 to the chamber 40, formed by the inner 'end of the recess 20 'and the inside face of the diaphragm, the breaks in the ridge 22 allowing the pressure within this chamber to be distributed evenly throughout the whole surface of the diaphragm. It' the air-pressure in this chamber be increased until it equalizes the resistance of the water, then obviously the gage upon the air-tank will indicate through the countervailing force said resistance. I

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have found it most efficacious to cause the countervailing pressure to exceed the resistance, which will be indicated in the currentindicator by the break of the current at the contact-points 30 land 38, and I then open the air-vent 58 and allow the vair to exhaust until there is the least sign, however slight, of current in the indicator. The pressure upon the inside of the diaphragm will then equalize the maximum resisting force upon the outside thereof. To ascertain the minimum resistance upon the pressure device, the countervailing force should be reduced until the current will run freely, except for a short interval, at which interval the indicator will indicate no current, which obviously will be caused by the countervailing force equalizing the resisting force only at the point of least resistance and causing a break in the current at the contactpoints 30 and 38. The maximum and minimum resistance to either of the pressure devices can be ascertained in this way, and with the maximum and minimum resistance to the defined area of the blade in which each device is located ascertained it is a simple matter to compute the average resistance to the Whole blade.

In order to ascertain the resistance to any particulardefmed area of the blade (by means of the pressure device located within that area) at the instant the blade passes through any predetermined angular plane, and therefore While the blade is instantaneously in that predetermined angular position, the countervailing force should be increased to exceed any possible resisting force, Y the clamping butterfly-nuts 134 loosened, and the ring 130 adjusted until the degree, upon the graduated rim thereon, corresponding to the angular plane in which it may be desired to obtain a reading, registers with the index-pointer upon the iiange 131. Upon the commutatin gswitch being then placed upon the beforementioned contact-point, the before-described reading can be had, but of the defined area, containing pressure device 1, when instantaneouslyin the angular position corresponding to said predetermined angular plane. In obtaining this latter reading the short-circuit switch should be opened, thus causing the current to flow from the battery through the current-indicator, conductor 14 to the adjustable contact device c, and through brush 114, contact-ring 118, sleeve 138, pin-head 140, contact-pin 121, contact-ring 117, brush 113, conductor 12, and thence, as before described, through the commutating-switch and pressure device to ground.

Although I have illustrated and described the preferred embodiment of my invention as applicable for ascertaining the resistance to propeller-blades, yet the same embodiment can be applied with substantially the same end in view to the immersed surface of the body of an ocean-going vessel or the like, or to the surface of the vanes of turbine Wheels, or, in fact, to any solid that acts upon or is acted upon by a flnid,or to any object, machine, or the like the resistance to or working pressure upon which it may be desired to ascertain, or to the surface of any other intermediary or agent other than a propeller through which motive power is derived by an object, machine, or the like from the resistance offered to said intermediary or agent or the pressure exerted thereupon by a fluid, whether liquid or gaseous, Without departing from the spirit of my invention.

It is obvious that moisture d ue to the sweating of the blade is liable to collect in the channelst, and if subjected to atemperature below freezing-point will freeze and prevent the variation in the pressure of the air being recorded from the pressure device to the pressure-gage upon the tank.; `I obviate this defect by providing a passage 150 in each pressure device and extending from the aft face thereof through the disk 23 to the nearest point in the air-chamber, this passage being screw-threaded at its outer end to receive a screw-threaded plug 151, by the removal of Which all moisture can be blown out of the chamber through said passages 150, The passages also enable the directions of currents from the propeller-blade to be ascertained by removing the plug and forcing a colored iiuid by means of the compressor through the pipes, coupler, shaft, channels, and said passage 150 into the water, wherein the currents will be indicated by said colored liquid, which will naturally iiow therewith.

Vhat I claim is as follows:

1. In combination with an immersed part of a marine vessel, a gage for ascertaining the resistance to or pressure upon the surface of said immersed part when said vessel is in motion comprising one or more pressure devices carried by the exposed surface of said immersed part, and with the outer face or faces thereof in contact with the Water 5 means for causing a countervailing force to act upon the inner face or faces of said pressure device or devices 5 `means for varying said countervailing forces; electrical means for indieating when said countervailing force equals the force of said resistance to or pressure upon the surface of said immersed part; and means for indicating the degree of said countervailing force.

2. In combination with a solid medium through which power is transmitted, a gage for ascertaining the resistance to or pressure upon the surface of said solid medium comprising one or more pressure devices carried by said medium; means for causing a countervailing force to act upon the face or faces of said pressure device or devices opposite to the face lor faces upon which said pressure is exerted or to which said resistance is offered; means for varying said countervailing force; electrical means for indicating when` said countervailing force equals the force of said resistance to or pressure upon the surface of said immersed part; and means for indicating the degree of said countervailing force.

3. In combination with an immersed part of a marine vessel, a gage for ascertaining the resistance to or pressure upon said immersed part and consisting of one or more pressure devices carried bythe immersed part and having the outer face or faces thereof in contact with the water in which said part is immersed; an air-tank; an air-compressor connected to said tank; a pressure-gage carried by said tank; an air-chamber located adjacent to and inclosing the rear face of each of said pressure devices; one or more air-conductors leading from said tank to said chamber or chambers 5 and electrical means for indicating when the pressure in said chamber or chambers equalizes the resistance of the water.

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4. A gage for ascertaining the resistancel to, or working pressure upon, any intermediary or agent through which motive power is derived by an object, machine, or the like, from the resistance odered to said intermediary or agent, or the pressure exerted thereupon by a fluid, whether liquid or gaseous, said gage consisting of one or more pressure devices carried lby the surface of said intermediary or agent and having the outer face or faces thereof in contact with said iiuid; an air-tank;

an air-compressor connected to said tank; a'

pressure-gage carried by said tank; an airchamber located adjacent to and inclosing the rear face of each of said pressure devices; one or more air-conductors leading from said tank to said chamber or chambers; an electric circuit comprising a battery, a contactpiece carried by each pressure device and a contact-piece carried adjacent to said firstmentioned con-tacts, by the body of the intermediary or agent, for indicating when the pressure in said chamber or chambers equalizes th-e resistance of the fluid.

5:. A gage for ascertaining the resistance to, or workin-g pressure upon, any intermediary or agent through which motive power is derived by an object, machine, or the like, from theresistance offered to said intermediary or agent, or the pressure exerted thereupon by a iiuid, whether liquid or gaseous, said gage col'isisting of one or more pressure devices carriedby the surface of said intermediary or agent and having the outer face or faces thereof in contact with said fluid; an air-tank; an air-compressor connected to said tank; a pressure-gage carried by said tank; an airch-amberlocated adj-acent to and inclosing the rear face of each of said pressure devices; one or more'air-condu'ctors leading fromsaid tank to sai-d chamber or chambers; means for indicating when the pressure in said chamber or chamibersequalizes the resistance of the tiuid; and means for causing said indication toI be given at any predetermined degree of the cycle of movement of said intermediary or agent.

6. A gage for ascertaining the resistance to, or working pressure upon, any intermediary or agent through which motive power is derived by an object, machine, or the like, from theA resistance offered tosaid intermediary or agent, or the pressure exerted thereupon by a fluid, whether liquid or gaseous, said gageconsisting of one or more pressure devices carried by the surface of said intermediary 0r agent and having they outer face or faces thereof inl con-tact with said fluid; an air-tank; an air-compressor connected to said tank; a pressure-gage carried by said tank; an ai-rchamber located adjacent to and inclosin g the rear facev of eachy of said pressure'devices ;k one or more' air-conductors leading from said tank to said chamber or chambers; an electric circuit comprisingabattery, a contact-piece carpiece carried adjacent to said first-mentioned j contacts by the body of the intermediary or agent, and for indicati-ng when the pressure in said chamber or chambers equalizes the resistance of the iuid; and means for causing said indication to be given atany predetermined degree of the cycle ot' movement of said intermediary or agent.

7. In combination with a hollow shaft and a blade of a propeller mounted thereon, a series of pressure devices carried by said blade and each consisting of a disk mounted in a i recess in the su-rface of said blade, the inner end of said recess constituting an air-chamber closed at its outer end by said disk; an air-channel leading from each of said chambers to the interior of the shaft, an air-tank; an air-tube leading from sa-id tank; means for coupling said air-pipe to a perforation in the shaft leading from the interior thereof; an air-compressor connected to said tank; a pressure-gageV mounted upon said air-tank; a contact-piece movable with said disk and projecting through the inside thereof; a contactpiece carried by the body of the blade adjacent to said first-mentioned contact-piece; means for insulating said last-mentioned contact-piece from the body of the blade; a series of contact rings encircling the shaft; means for connecting said rings rigidly to the shaft; a series of insu-lated conductors elecf trically connecting said rings respectively to the last-mentioned contact-pieces of the preslsure device, a stationary frame;- a series of g electrical brushes carried by said framev and ieach bea-ring upon one of the said contact- 1 rings; a commutating-switch a series of conl ductors electrically connecting said contactf rings to said com'm'utating-switch ;V a currentliindicator; a conductor electrically connecting said current-indicator to the lever of said 1 commutating-switch; and an electric battery with ground connection electricallyconnected to said indicator, substantially as described 5 and for the purpose set forth.

8. In combination withv a hollow shaft and I a blade of a propeller mounted thereon', a series of pressure devices carried by said blade and each consisting of a resilient diaphragm amounted in a recess in the surface of said blade, the inner end of said recess constitu-t- E ing an air-chamber closed at its outer end by isaid diaphragm; air-channels leading from f each of said chambers to the interior of the shaft; an air-tank; an air-pipe leading from said tank; means for coupling said air-pipe to a perforation in the shaft leading from the interior thereof; Aan air-compressor connectled to said tank; a pressuregage mounted upon said air-tank; a contact-piece movable with each of said diaphragms, and projecting lthrough the insidey thereof; a contact-piece carried by the body of the blade adjacent to feach of said first-mentioned contact-pieces; mea-ns for insulating said last-mentioned! contact-pieces from the body of the blade; a comzmlutating-switch; a short-circuit. switch; a

fcurrent-indicator; an electric battery; col:-

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lecting means for electrically connecting the contact-points of said commutating-switch to the contact-pieces carried by the body of the blade; a main `electric circuit including said battery, current-indicator, switch, collecting means, and contact-pieces; adjustable contact means comprising a contact-piece rotatable with the shaft; a part adj ustable around said shaft and a contact-piece carried by said adjustable part and located in the line of movement of the contact-piece rotatable with the shaft; a branch circuit from one to the other of the terminals of said short-circuit switch and including` said adjustable Contact means, substantially as and for the purpose set forth.

D. In combination with a propeller-blade of a marine vessel, a gage substantially as described for ascertaining the resistance to said propeller-blade, a hollow shaft for rotating said propeller and having an air-chamber in the interior thereof, said air-chamber communicating with the exterior by a boring; an air-compressor; an air-conducting pipe leading from said compressor toward said boring; a device for coupling said pipe to said airchamber, comprising a stationary annulus having a pair of centrolineallyextending iianges fitting the exterior of said shaft one' on each side of said boring; a pair of stuiiingboxes hermetically sealing the spaces between the edges of said annulus and the shaft; means for retaining said annulus against rotation; said pipe being connected to the chamber formed by said annulus, substantially as described and for the purpose set forth.

10. In combination with a propeller-blade of a marine vessel, a series of electrical contacts yieldingly carried by the propellerblade, each contact having one of its faces exposed; a second series of electrical contacts carried by said propeller-blade in close proximity to but normally out of contact with the inner or unexposed faces of said first series of contacts, a hollowT shaft for rotating said propeller and having a radial boring therethrough; a circular box encircling said shaft; means for rigidly connecting said box to said shaft; a series of contact-rings, encircling said box and rigidly carried thereby and insulated therefrom; a series of electrical conductors located within said shaft and extending through said boring and each being electrically connected at one end to one of the rings of said series and at its other end to one of said second contacts; a part mounted stationary within the vessel; a series of brushes carried by said stationary part and bearing upon said contact-rings; an electric generator; a switchboard comprising a switch and a series of terminals; a current-indicator; a conductor connecting said generator to the current-indicator and the current-indicator to the switch of said switchboard; a series of conductors connecting the terminals of said switchboard to -said series of brushes; substantially as described and for the purpose g set forth.

ll. In a gage substantially as described for ascertaining the resistance to propellerblades, at any predetermined angular position during their revolution, the combination of an electric circuit, substantially as described and including a short-circuit switch; a circular box encircling said shaft; means for rigidly connecting said box to said shaft; a contact-ring encircling said box and rigidly carried therebyand insulated therefrom; a contact-piece carried by said box and insulated therefrom and in electrical contactwith said contact-ring; a frame having an annular extension adapted to encircle said box adjacent to said contact-ring; means for retaining said frame againstrotation with the shaft; an adjustable carrying-rin g rotatably mounted upon and encircling said annular extension; means for connecting and disconnecting said ring and annular extension; a contact-ring encircling said carryingring and rigidly carried thereby and insulated therefrom; a yielding contact-piece carried by said carrying-ring, and insulated therefrom and in electrical contactwith said last-mentioned contact-ring; a pairof brushes insulated from one another and carried by and insulated from said stationary frame, said brushes bearing respectively upon said contact-rings; and a branch circuit from terminal to terminal of said short-circuit switch and including said contact-rings, substantially as described and for the purpose set forth.

l2. In a vessel, the combination of a shaft having a longitudinal passage, a propeller mounted on said shaft,one of the blades of said propeller being provided with one or more passages each communicating at one end with the passage in the shaft and at its other end with an opening extending to the surface of said blade, and means for forcing avfiuid through said passages, for the purpose set forth.

13. In combination witha hollow propellershaft, and a propeller mounted thereon, one of the blades whereof is provided with one or more passages each leading from the aft toward the forward face thereof; said passage or passages each having a removable plugin the end or ends thereof one or more channels leading from said passage or passages to the interior of the shaft, said shaft having an additional passage from the interior to the exterior thereof; a compressor, a pipe leading from said compressor to the last-mentioned passage, and means for coupling said passage and pipe together, whereby the shaft will be free to rotate while the pipe will remain stationary, for the purpose set forth.

In testimony whereof I have afxed my signature in presence of two witnesses.

` PHILIP J. DARLINGTON. Witnesses: i

WILLIAM P. MGFEAT, FRED. J. SEARS.

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